Pitkin County is now the second county in Colorado that can issue permits for graywater systems that allow some household water to be reused to irrigate lawns and flush toilets.

Graywater is defined by both the county and the state as water coming from bathtubs, showers, bathroom sinks and washing machines. It does not include water from toilets, urinals, kitchen sinks, dishwashers or non-laundry utility sinks, which is often called blackwater.

The city and county of Denver was the first to adopt a similar permitting process in 2016, and did so after the state approved guiding regulations in 2015. The Pitkin County commissioners unanimously approved an ordinance last week that sets up the county’s permitting process, which is voluntary.

The city of Aspen also is considering adopting a graywater permitting system to complement its recently adopted water-efficient landscaping regulations.

Kurt Dahl, the county’s environmental health manager, said a 1999 statewide study found that typical indoor residential uses amounted to 69 gallons of water per person per day, and of that 28 gallons is graywater as defined by the state.

Graywater systems work by diverting household water away from its normal course — toward septic tanks and sewage systems — and into another set of pipes and storage tanks, where it sits until it is reused.

If the water is used for irrigation, the water must be filtered before storage and then, optimally, pumped out into a subsurface drip irrigation system. It cannot be applied via sprinklers.

If graywater is used to flush toilets, it must be disinfected and dyed before being sent to a toilet.

Single-family households can store up to 400 gallons of water a day in a tank for either irrigation or toilet flushing, and multi-family and commercial entities can store up to 2,000 gallons a day.

Graywater systems require double-piping of plumbing systems, which can be expensive to install in existing homes, and so may be better suited, at least economically, to new construction projects.

Brett Icenogle, the engineering section manager at the Colorado Department of Public Health, said Friday he was happy to see Pitkin County adopt a graywater permitting process, and he hopes other jurisdictions follow suit, even if current public demand seems low today.

“We don’t want to wait until there is a water shortage to put regulations in place,” Icenogle said.

The local permitting process begins with the county’s environmental health department, and also requires plumbing and building permits. If used for irrigation, it may also require a state water right.

Dahl served on a group that developed the state’s regulations, and he’d like to see other uses added to the state’s list, such as fire suppression.

“I want to get this to the point where using graywater is an option for everyone,” Dahl said.